JP2003336009A - Coating composition for producing insulation thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous silica thin film which has a low relative dielectric constant and is suitable as an insulation film of a semiconductor element, and a composition solution for producing the film which excels in storage stability. <P>SOLUTION: The coating composition comprises a silica precursor containing at least one compound selected from a specific mono- to hexafunctional alkoxysilane, its hydrolyzate, and its polycondensate and an organic polymer containing a branched organic polymer bonded to a two- or more-component aliphatic ether block copolymer through a connecting group having at least three carbon-oxygen bonds. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating composition having excellent storage stability, which can provide a thin film having a sufficiently low relative dielectric constant.

[0002]

2. Description of the Related Art Porous silica is widely used as a structural material, a catalyst carrier, an optical material and the like because it has excellent properties such as light weight and heat resistance. For example, in recent years, expectations have been gathered from the viewpoint that porous silica can lower the dielectric constant. Conventionally, a dense silica film has been generally used as an insulating thin film material for a multilayer wiring structure of a semiconductor device such as an LSI. However, in recent years, the wiring density of LSIs has been miniaturized, and the distance between adjacent wirings on the substrate has been narrowed accordingly. At this time, if the dielectric constant of the insulator is high, the capacitance between the wirings increases, and as a result, the delay of the electric signal transmitted through the wiring becomes significant, which is a problem. In order to solve such a problem, a material having a lower dielectric constant is strongly required as a material for an insulating film for a multilayer wiring structure. On the other hand, the fact that copper having a lower resistance has begun to be used as a wiring material in place of conventional aluminum is another reason why a substance having a lower dielectric constant is required.

In Japanese Patent Laid-Open No. 5-85762 and International Publication (WO) 99/03926, a mixture system of a general alkoxysilane and an organic polymer has an extremely low dielectric constant, uniform pores and pore distribution. There is disclosed a method for obtaining porous silica having a porosity. Further, in JP-A-4-285081, a sol-gel reaction of alkoxysilane is carried out in the presence of a specific organic polymer, and then the organic polymer is removed to obtain porous silica having a uniform pore size. A method is disclosed.

Further, in Japanese Patent Laid-Open No. 2001-49184, bifunctional, trifunctional, and tetrafunctional alkoxysilanes are charged in such a manner that two silicon atoms are contained in the molecule.
The amount of hexafunctional alkoxysilane is more than the charged amount, a block copolymer is used as an organic polymer, and after performing a sol-gel reaction, the organic polymer is removed in the same manner as described above to have excellent dielectric constant characteristics and water absorption, and A method of forming a low density film having a small void size is disclosed.

However, a coating solution containing the above-mentioned alkoxysilane and an organic polymer, which is generally used for forming a film, has a problem that it is partially solidified when stored at a low temperature. There is also a problem that the viscosity of the solution becomes too high when handled at room temperature. In order to solve these problems, a method of reducing the molecular weight of the polymer, or using an organic solvent having a relatively high boiling point instead of the polymer may be used. There is a problem that a porous silica film as designed cannot be obtained because the organic matter in a portion is volatilized, and it is necessary to lower the melting point and the viscosity while keeping the molecular weight of the polymer constant.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, in which a porous insulating silica thin film has a low relative permittivity, is stable, and has excellent storage stability of a solution. The present invention provides a coating composition for producing an insulating silica thin film.

[0007]

In order to solve the above problems, the inventors of the present invention have conducted extensive studies, and as a result, formed a carbon-oxygen bond in place of a general linear polymer as an organic polymer. The storage stability of the coating composition is a linking group having at least 3 possible linking parts, and at least 3 of the linking parts contain a branched organic polymer which is bonded to a block copolymer of two or more elements. Have been found to significantly improve.

The above and other objects, characteristics, and benefits of the present invention will be apparent from the detailed description and claims below. The porous silica referred to in the present invention is characterized by being a porous silica whose main component is represented by the following formula (3). R _x H _y SiO _z (3) (R represents a linear, branched or cyclic alkyl group or aryl group having 1 to 8 carbon atoms, 0 ≦ x <2, 0 ≦ y <2,
0 ≦ (x + y) <2 and 1 <z ≦ 2. )

In the alkoxysilane represented by the general formula (1) described above in the present invention, Si (O
R ₂ ) ₄ is called a tetrafunctional alkoxysilane, and when n is 1 in the general formula (1), that is, R ¹ (Si) (OR ² ) ₃ is a trifunctional alkoxysilane and n is 2. , That is, R ¹ ₂
(Si) (OR ² ) ₂ is a bifunctional alkoxysilane, n
Is 3, that is, R ¹ ₃ (Si) (OR ² ) is a monofunctional alkoxysilane. Further, the alkoxysilane represented by the general formula (2), for example, m = q = 1 with _{^{R 3 (R 4 O) 2}} Si- and _{^{(R 7) p -Si (OR}} 5) compounds of the ₂ R ⁶ 4 functional alkoxysilane, at m = 0, q = 1 or m = 1, q = 0, (R 4 O) 3 Si- (R 7) p -S
The compound of i (OR ⁵ ) ₂ R ⁶ is a pentafunctional alkoxysilane, m = q = 0, and (R ⁴ O) ₃ Si— (R ⁷ ) _p —Si (O
The compound of R ⁵ ) ₃ is a hexafunctional alkoxysilane, and m = q = 2 in the general formula (2), that is, R ³ ₂ (R ⁴ O) Si
- In _{^{(R 7) p -Si (OR}} 5) R 6 2 a bifunctional alkoxysilane, m = 2, q = 1 or m = 1, q = 2, R 3 2
And ^{(R 4 O) Si- (R} 7) p -Si (OR 5) compound trifunctional ₂ R ⁶ alkoxysilane. In the present invention, the alkoxysilane is hydrolyzed and polycondensed so that the condensation rate exceeds 90%.

The coating composition for producing an insulating thin film (hereinafter referred to as the coating composition) used in the present invention will be described below. The coating composition used in the present invention contains a silica precursor containing at least one of alkoxysilane, a hydrolyzate and a polycondensate thereof, an organic polymer and a solvent as main components.

First, the silica precursor (A) used in the present invention will be described. The alkoxysilane represented by the general formula (1) and its hydrolyzate and polycondensate contained in the silica precursor that can be used in the present invention have a starting material of alkoxysilane having 4, 3, 2 and 1 functions. It is of sex. The alkoxysilane and its hydrolyzate and polycondensate are hereinafter referred to as alkoxysilane and the like.

Specific examples of the tetrafunctional alkoxysilane among the alkoxysilanes represented by the general formula (1) include tetramethoxysilane, tetraethoxysilane, tetra (n-propoxy) silane, and tetra (i-propoxy). ) Silane, tetra (n-butoxy) silane, tetra-
Examples thereof include sec-butoxysilane and tetra-tert-butoxysilane.

Specific examples of trifunctional alkoxysilanes among the alkoxysilanes represented by the general formula (1) include trimethoxysilane, triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane and ethyltrimethoxysilane. , Ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane,
Isobutyltriethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, methyltri-n-propoxysilane, methyltri-iso. -Propoxysilane, methyltri-n-butoxysilane, methyltri-sec-butoxysilane, methyltri-tert-butoxysilane, ethyltri-n-propoxysilane, ethyltri-
iso-propoxysilane, ethyltri-n-butoxysilane, ethyltri-sec-butoxysilane, ethyltri-tert-butoxysilane, n-propyltri-
n-propoxysilane, n-propyltri-iso-propoxysilane, n-propyltri-n-butoxysilane, n-propyltri-sec-butoxysilane, n-
Propyltri-tert-butoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, i-propyltri-n-propoxysilane, i-propyltri-iso-propoxysilane, i-propyltri-n-butoxy Silane, i-propyltri-sec
-Butoxysilane, i-propyltri-tert-butoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-butyltri-n-propoxysilane, n-butyltri-iso-propoxysilane, n-butyltri- n-butoxysilane, n-butyltri-sec-butoxysilane, n-butyltri-te
rt-Butoxysilane, n-butyltriphenoxysilane, sec-butyltrimethoxysilane, sec-butyl-tri-n-propoxysilane, sec-butyl-tri-iso-propoxysilane, sec-butyl-tri-n-butoxy. Silane, sec-butyl-tri-sec
-Butoxysilane, sec-butyl-tri-tert-
Butoxysilane, t-butyltrimethoxysilane, t-
Butyltriethoxysilane, t-butyltri-n-propoxysilane, t-butyltri-iso-propoxysilane, t-butyltri-n-butoxysilane, t-butyltri-sec-butoxysilane, t-butyltri-t.
ert-butoxysilane, phenyltri-n-propoxysilane, phenyltri-iso-propoxysilane,
Phenyltri-n-butoxysilane, phenyltri-s
Examples include ec-butoxysilane and phenyltri-tert-butoxysilane.

Of these tetrafunctional and trifunctional alkoxysilanes, tetramethoxysilane, tetraethoxysilane, trimethoxysilane, triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane and dimethyldimethoxysilane are particularly preferable. It is dimethyldiethoxysilane.

Specific examples of the bifunctional alkoxysilane represented by the general formula (1) include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi (n-propoxy) silane, dimethyldi (i-propoxy) silane, Dimethyldi (n-butoxy) silane, dimethyldi (sec-butoxy) silane, dimethyldi (tert-)
Butoxysilane), diethyldimethoxysilane, diethyldiethoxysilane, diethyldi (n-propoxy) silane, diethyldi (i-propoxy) silane, diethyldi (n-butoxy) silane, diethyldi (sec-butoxy) silane, diethyldi (tert-butoxy). Silane), diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldi (n-propoxy) silane,
Diphenyldi (i-propoxy) silane, diphenyldi (n-butoxy) silane, diphenyldi (sec-butoxy) silane, diphenyldi (tert-butoxysilane), methylethyldimethoxysilane, methylethyldiethoxysilane, methylethyldi (n -Propoxy) silane, methylethyldi (i-propoxy) silane, methylethyldi (n-butoxy) silane, methylethyldi (sec-butoxy) silane, methylethyldi (ter)
t-butoxysilane), methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylpropyldi (n-propoxy) silane, methylpropyldi (i-
Propoxy) silane, methylpropyldi (n-butoxy) silane, methylpropyldi (sec-butoxy) silane, methylpropyldi (tert-butoxysilane), methylphenyldimethoxysilane, methylphenyldiethoxysilane, methylphenyldi (n -Propoxy) silane, methylphenyldi (i-propoxy) silane, methylphenyldi (n-butoxy) silane, methylphenyldi (sec-butoxy) silane, methylfaildi (tert-butoxysilane), ethylphenyldimethoxysilane, Ethylphenyldiethoxysilane, ethylphenyldi (n-propoxy) silane, ethylphenyldi (i-propoxy) silane, ethylphenyldi (n-butoxy) silane, ethylphenyldi (sec-
Examples thereof include butoxy) silane, ethylphenyldi (tert-butoxysilane), and other alkylsilanes in which two alkyl groups or aryl groups are bonded to a silicon atom.

Further, methylvinyldimethoxysilane, methylvinyldiethoxysilane, methylvinyldi (n-propoxy) silane, methylvinyldi (i-propoxy)
Silane, methylvinyldi (n-butoxy) silane, methylvinyldi (sec-butoxy) silane, methylvinyldi (tert-butoxysilane), divinyldimethoxysilane, divinyldiethoxysilane, divinyldi (n-
Propoxy) silane, divinyldi (i-propoxy) silane, divinyldi (n-butoxy) silane, divinyldi (sec-butoxy) silane, divinyldi (tert-)
Butoxysilane), and other alkylsilanes having 1 or 2 vinyl groups bonded to silicon atoms are also suitable.

Specific examples of the monofunctional alkoxysilane represented by the general formula (1) include trimethylmethoxysilane, trimethylethoxysilane, trimethyl (n-propoxy) silane, trimethyl (i-propoxy) silane and trimethyl (n). -Butoxy) silane, trimethyl (sec-butoxy) silane, trimethyl (tert-)
Butoxysilane), triethylmethoxysilane, triethylethoxysilane, triethyl (n-propoxy) silane, triethyl (i-propoxy) silane, triethyl (n-butoxy) silane, triethyl (sec-butoxy) silane, triethyl (tert-butoxysilane). ), Tripropylmethoxysilane, tripropylethoxysilane, tripropyl (n-propoxy) silane,
Tripropyl (i-propoxy) silane, tripropyl (n-butoxy) silane, tripropyl (sec-butoxy) silane, tripropyl (tert-butoxysilane), triphenylmethoxysilane, triphenylethoxysilane, triphenyl (n -Propoxy) silane,
Triphenyl (i-propoxy) silane, triphenyl (n-butoxy) silane, triphenyl (sec-butoxy) silane, triphenyl (tert-butoxysilane), methyldiethylmethoxysilane, methyldiethylethoxysilane, methyldiethyl (n -Propoxy) silane, methyldiethyl (i-propoxy) silane, methyldiethyl (n-butoxy) silane, methyldiethyl (sec-butoxy) silane, methyldiethyl (ter)
t-butoxysilane), methyldipropylmethoxysilane, methyldipropylethoxysilane, methyldipropyl (n-propoxy) silane, methyldipropyl (i-
Propoxy) silane, methyldipropyl (n-butoxy) silane, methyldipropyl (sec-butoxy) silane, methyldipropyl (tert-butoxysilane), methyldiphenylmethoxysilane, methyldiphenylethoxysilane, methyldiphenyl (n-propoxy) ) Silane, methyldiphenyl (i-propoxy) silane, methyldiphenyl (n-butoxy) silane, methyldiphenyl (sec-butoxy) silane, methyldiphenyl (tert-butoxysilane), ethyldimethylmethoxysilane, ethyldimethylethoxysilane, ethyl Dimethyl (n-propoxy) silane, ethyldimethyl (i-propoxy) silane, ethyldimethyl (n-butoxy) silane, ethyldimethyl (sec-butoxy) silane, ethyldimethyl (t rt- butoxysilane),
Ethyldipropylmethoxysilane, ethyldipropylethoxysilane, ethyldipropyl (n-propoxy) silane, ethyldipropyl (i-propoxy) silane, ethyldipropyl (n-butoxy) silane, ethyldipropyl (sec-butoxy) Silane, ethyldipropyl (tert-butoxysilane), ethyldiphenylmethoxysilane, ethyldiphenylethoxysilane, ethyldiphenyl (n-propoxy) silane, ethyldiphenyl (i-propoxy) silane, ethyldiphenyl (n-
Butoxy) silane, ethyldiphenyl (sec-butoxy) silane, ethyldiphenyl (tert-butoxysilane), propyldimethylmethoxysilane, propyldimethylethoxysilane, propyldimethyl (n-propoxy) silane, propyldimethyl (i-propoxy) silane, Propyldimethyl (n-butoxy) silane, propyldimethyl (sec-butoxy) silane, propyldimethyl (tert-butoxysilane), propyldiethylmethoxysilane, propyldiethylethoxysilane,
Propyldiethyl (n-propoxy) silane, propyldiethyl (i-propoxy) silane, propyldiethyl (n-butoxy) silane, propyldiethyl (sec-
Butoxy) silane, propyldiethyl (tert-butoxysilane), propyldiphenylmethoxysilane, propyldiphenylethoxysilane, propyldiphenyl (n-propoxy) silane, propyldiphenyl (i-
Propoxy) silane, propyldiphenyl (n-butoxy) silane, propyldiphenyl (sec-butoxy)
Silane, propyldiphenyl (tert-butoxysilane) phenyldimethylmethoxysilane, phenyldimethylethoxysilane, phenyldimethyl (n-propoxy) silane, phenyldimethyl (i-propoxy) silane, phenyldimethyl (n-butoxy) silane, phenyldimethyl ( sec-butoxy) silane, phenyldimethyl (tert-butoxysilane), phenyldiethylmethoxysilane, phenyldiethylethoxysilane, phenyldiethyl (n-propoxy) silane, phenyldiethyl (i-propoxy) silane, phenyldiethyl (n-butoxy) Silane, phenyldiethyl (sec-
Butoxy) silane, phenyldiethyl (tert-butoxysilane), phenyldipropylmethoxysilane, phenyldipropylethoxysilane, phenyldipropyl (n-propoxy) silane, phenyldipropyl (i-
Propoxy) silane, phenyldipropyl (n-butoxy) silane, phenyldipropyl (sec-butoxy)
Examples thereof include silane and phenyldipropyl (tert-butoxysilane).

Alkylsilanes having 1 to 3 vinyl groups bonded to silicon atoms are also suitable. Specifically, trivinylmethoxysilane, trivinylethoxysilane, trivinyl (n-propoxy) silane, trivinyl (i-propoxy) silane, trivinyl (n-butoxy) silane, trivinyl (sec-butoxy) silane,
Trivinyl (tert-butoxysilane), vinyldimethylmethoxysilane, vinyldimethylethoxysilane,
Vinyldimethyl (n-propoxy) silane, vinyldimethyl (i-propoxy) silane, vinyldimethyl (n-)
Butoxy) silane, vinyldimethyl (sec-butoxy) silane, vinyldimethyl (tert-butoxysilane), vinyldiethylmethoxysilane, vinyldiethylethoxysilane, vinyldiethyl (n-propoxy) silane, vinyldiethyl (i-propoxy) silane, Vinyldiethyl (n-butoxy) silane, vinyldiethyl (sec-butoxy) silane, vinyldiethyl (ter)
t-butoxysilane), vinyldipropylmethoxysilane, vinyldipropylethoxysilane, vinyldipropyl (n-propoxy) silane, vinyldipropyl (i-
Propoxy) silane, vinyldipropyl (n-butoxy) silane, vinyldipropyl (sec-butoxy) silane, vinyldipropyl (tert-butoxysilane)
And so on.

Next, in the alkoxysilanes represented by the general formula (2) which can be used in the present invention, the starting materials are alkoxysilanes 6, 5, 4, 3 and 2
It is sensual. Of the alkoxysilanes represented by the general formula (2), R ⁷ is a compound of — (CH ₂ ) _n —,
Specific examples of the 5-, 4-, 3-, and 2-functional alkoxysilanes include bis (trimethoxysilyl) methane, bis (triethoxysilyl) methane, and bis (triphenoxysilyl) methane as examples of the hexafunctional alkoxysilane. ,
Bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, bis (triphenoxysilyl) ethane, 1,3-bis (trimethoxysilyl) propane,
1,3-bis (triethoxysilyl) propane, 1,3
Examples include -bis (triphenoxysilyl) propane, 1,4-bis (trimethoxysilyl) benzene, and 1,4-bis (triethoxysilyl) benzene.

As the pentafunctional alkoxysilane, 1-
(Dimethoxymethylsilyl) -1- (trimethoxysilyl) methane, 1- (diethoxymethylsilyl) -1-
(Triethoxysilyl) methane, 1- (di-n-propoxymethylsilyl) -1- (tri-n-propoxysilyl) methane, 1- (di-i-propoxymethylsilyl)
-1- (tri-i-propoxysilyl) methane, 1-
(Di-n-butoxymethylsilyl) -1- (tri-n-
Butoxysilyl) methane, 1- (di-sec-butoxymethylsilyl) -1- (tri-sec-butoxysilyl) methane, 1- (di-t-butoxymethylsilyl)-
1- (tri-t-butoxysilyl) methane, 1- (dimethoxymethylsilyl) -2- (trimethoxysilyl) ethane, 1- (diethoxymethylsilyl) -2- (triethoxysilyl) ethane, 1- ( Di-n-propoxymethylsilyl) -2- (tri-n-propoxysilyl) ethane, 1- (di-i-propoxymethylsilyl) -2-
(Tri-i-propoxysilyl) ethane, 1- (di-n
-Butoxymethylsilyl) -2- (tri-n-butoxysilyl) ethane, 1- (di-sec-butoxymethylsilyl) -2- (tri-sec-butoxysilyl) ethane, 1- (di-t-butoxy Methylsilyl) -2- (tri-t-butoxysilyl) ethane and the like.

Examples of tetrafunctional alkoxysilanes are bis (dimethoxymethylsilyl) methane, bis (diethoxymethylsilyl) methane, bis (dimethoxyphenylsilyl) methane, bis (diethoxyphenylsilyl) methane, bis (dimethoxymethyl). (Silyl) ethane, bis (diethoxymethylsilyl) ethane, bis (dimethoxyphenylsilyl) ethane, bis (diethoxyphenylsilyl) ethane, 1,3-bis (dimethoxymethylsilyl)
Examples thereof include propane, 1,3-bis (diethoxymethylsilyl) propane, 1,3-bis (dimethoxyphenylsilyl) propane, 1,3-bis (diethoxyphenylsilyl) propane and the like.

As the trifunctional alkoxysilane, 1-
(Dimethoxymethylsilyl) -1- (methoxydimethylsilyl) methane, 1- (diethoxymethylsilyl) -1
-(Ethoxydimethylsilyl) methane, 1- (di-n-
Propoxymethylsilyl) -1- (n-propoxydimethylsilyl) methane, 1- (di-i-propoxymethylsilyl) -1- (i-propoxydimethylsilyl) methane, 1- (di-n-butoxymethylsilyl) ) -1- (n
-Butoxydimethylsilyl) methane, 1- (di-sec
-Butoxymethylsilyl) -1- (sec-butoxydimethylsilyl) methane, 1- (di-t-butoxymethylsilyl) -1- (t-butoxydimethylsilyl) methane, 1- (dimethoxymethylsilyl) -2- (Methoxydimethylsilyl) ethane, 1- (diethoxymethylsilyl) -2- (ethoxydimethylsilyl) ethane, 1-
(Di-n-propoxymethylsilyl) -2- (n-propoxydimethylsilyl) ethane, 1- (di-i-propoxymethylsilyl) -2- (i-propoxydimethylsilyl) ethane, 1- (di-n -Butoxymethylsilyl)
-2- (n-butoxydimethylsilyl) ethane, 1-
(Di-sec-butoxymethylsilyl) -2- (sec
-Butoxydimethylsilyl) ethane, 1- (di-t-butoxymethylsilyl) -2- (t-butoxydimethylsilyl) ethane and the like.

Specific examples of the bifunctional alkoxysilane include bis (methoxydimethylsilyl) methane, bis (ethoxydimethylsilyl) methane, bis (methoxydiphenylsilyl) methane, bis (ethoxydiphenylsilyl) methane and bis (methoxydimethyl). Cyril) ethane,
Bis (ethoxydimethylsilyl) ethane, bis (methoxydiphenylsilyl) ethane, bis (ethoxydiphenylsilyl) ethane, 1,3-bis (methoxydimethylsilyl) propane, 1,3-bis (ethoxydimethylsilyl) propane, 1, Examples thereof include 3-bis (methoxydiphenylsilyl) propane and 1,3-bis (ethoxydiphenylsilyl) propane.

Hexamethoxydisiloxane, hexaethoxydisiloxane, hexaphenoxydisiloxane, 1,1,1,3,3- as the hexafunctional alkoxysilane in which R ⁷ is an oxygen atom in the general formula (2) Pentamethoxy-3-methyldisiloxane, 1,1,1,3,3-pentaethoxy-3 as a pentafunctional alkoxysilane
-Methyldisiloxane, 1,1,1,3,3-pentamethoxy-3-phenyldisiloxane, 1,1,1,3
3-Pentaethoxy-3-phenyldisiloxane, 1,1,3,3-tetramethoxy-1,3-dimethyldisiloxane as a tetrafunctional alkoxysilane, 1,1,
3,3-tetraethoxy-1,3-dimethyldisiloxane, 1,1,3,3-tetramethoxy-1,3-diphenyldisiloxane, 1,1,3,3-tetraethoxy-
1,3-diphenyldisiloxane, 1,1,3-trimethoxy-1,3,3 as trifunctional alkoxysilane
-Trimethyldisiloxane, 1,1,3-triethoxy-1,3,3-trimethyldisiloxane, 1,1,3-
Trimethoxy-1,3,3-triphenyldisiloxane, 1,1,3-triethoxy-1,3,3-triphenyldisiloxane, 1,3-dimethoxy-1,1,3 as a bifunctional alkoxysilane , 3-tetramethyldisiloxane, 1,3-diethoxy-1,1,3,3-tetramethyldisiloxane, 1,3-dimethoxy-1,
1,3,3-tetraphenyldisiloxane, 1,3-diethoxy-1,1,3,3-tetraphenyldisiloxane, 3-dimethoxy-1,1,3,3-tetramethyldisiloxane, 1,3 -Diethoxy-1,1,3,3-tetramethyldisiloxane, 1,3-dimethoxy-1,
Examples include 1,3,3-tetraphenyldisiloxane and 1,3-diethoxy-1,1,3,3-tetraphenyldisiloxane.

In the general formula (2), a compound in which p is 0 is 6,
Specific examples of 5-, 4-, 3- and 2-functional alkoxysilanes include 6-functional alkoxysilanes such as hexamethoxydisilane, hexaethoxydisilane, hexaphenyldidisilane and 5-functional alkoxysilanes. 1,1,1,2,2-pentamethoxy-2
-Methyldisilane, 1,1,1,2,2-pentaethoxy-2-methyldisilane, 1,1,1,2,2-pentamethoxy-2-phenyldisilane, 1,1,1,2,2
-Pentaethoxy-2-phenyldisilane, specific examples of tetrafunctional alkoxysilane are 1,1,2,2-tetramethoxy-1,2-dimethyldisilane, 1,1,2,
2-tetraethoxy-1,2-dimethyldisilane, 1,
Specific examples of 1,2,2-tetramethoxy-1,2-diphenyldisilane, 1,1,2,2-tetraethoxy-1,2-diphenyldisilane and trifunctional alkoxysilane are 1,1,2- Trimethoxy-1,2,2-trimethyldisilane, 1,1,2-triethoxy-1,2,2
-Trimethyldisilane, 1,1,2-trimethoxy-
Specific examples of 1,2,2-triphenyldisilane, 1,1,2-triethoxy-1,2,2-triphenyldisilane and bifunctional alkoxysilane are 1,2-dimethoxy-1,1,2, 2-tetramethyldisilane, 1,2-
Diethoxy-1,1,2,2-tetramethyldisilane,
Examples thereof include 1,2-dimethoxy-1,1,2,2-tetraphenyldisilane and 1,2-diethoxy-1,1,2,2-tetraphenyldisilane.

The above-mentioned alkoxysilanes are used as the mono-, di- and tri-functional alkoxysilanes of the present invention. Among them, more preferred are the monofunctional and difunctional alkoxysilanes of the present invention. As the alkoxysilane, the above-mentioned alkoxysilane is used, but among them, more preferable are trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, triethylethoxysilane, tripropylmethoxysilane, tripropylethoxysilane, and tripropylethoxysilane. Three alkyl or aryl groups are directly bonded to a silicon atom such as phenylmethoxysilane, triphenylethoxysilane, phenyldimethylmethoxysilane, phenyldimethylethoxysilane, diphenylmethylmethoxysilane and diphenylmethylethoxysilane. Alkylsilane, and dimethyldiethoxysilane, diethyldiethoxysilane, diphenyldiethoxysilane, methylethyldiethoxysilane, methylphenyldiethoxysilane, ethylphenyldiethoxysilane, dimethyldimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane , Diphenyldimethoxysilane, methylethyldimethoxysilane, methylphenyldimethoxysilane, ethylphenyldimethoxysilane, and other alkylsilanes in which two alkyl groups or aryl groups are directly bonded to a silicon atom.

Further, methyldimethoxysilane, methyldiethoxysilane, ethyldimethoxysilane, ethyldiethoxysilane, propyldimethoxysilane, propyldiethoxysilane, dimethylvinylmethoxysilane, dimethylvinylethoxysilane, phenyldimethoxysilane, phenyldiethoxysilane. And alkoxysilanes in which one alkyl group or aryl group is directly bonded to a silicon atom. Furthermore, bis (ethoxydimethylsilyl) methane, bis (ethoxydiphenylsilyl)
Methane, bis (ethoxydimethylsilyl) ethane, bis (ethoxydiphenylsilyl) ethane, 1,3-bis (ethoxydimethylsilyl) propane, 1,3-bis (ethoxydiphenylsilyl) propane, 3-diethoxy-1,1, 3,3-tetramethyldisiloxane, 1,
3-diethoxy-1,1,3,3-tetraphenyldisiloxane, 1,2-diethoxy-1,1,2,2-tetramethyldisilane, 1,2-diethoxy-1,1,2,
2-Tetraphenyldisilane and the like can be preferably used.

Among these, particularly preferable alkoxysilanes are trimethylethoxysilane, triethylethoxysilane, tripropylethoxysilane, triphenylethoxysilane, phenyldimethylethoxysilane,
Examples thereof include diphenylmethylethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, diphenyldiethoxysilane, methylethyldiethoxysilane, methylphenyldiethoxysilane and ethylphenyldiethoxysilane.

The silica precursor of the present invention contains at least one or more of the above alkoxysilanes and their hydrolyzed and polycondensed products. The hydrolyzate also includes a partial hydrolyzate. For example, silica precursor (A)
In the case of the tetrafunctional alkoxysilane used for, it is not necessary that all four alkoxys be hydrolyzed, for example, only one is hydrolyzed, two or more are hydrolyzed, Alternatively, a mixture of these may be present. Further, the polycondensate contained in the silica precursor (A) in the present invention means that the silanol group of the hydrolyzate of the silica precursor (A) is condensed to form Si.
Although it forms a —O—Si bond, it does not need to have all the silanol groups condensed, and represents a mixture of some of the silanol groups, a mixture of different degrees of condensation, and the like.

The content of the silica precursor in the coating composition of the present invention can be expressed as the total solid content concentration. As will be described later, the total solid content concentration is preferably 2 to 30% by weight, depending on the thickness of the target insulating thin film, and the storage stability is excellent. The total solid content concentration is a known amount of the coating composition of the present invention, that is, the total amount of the charged alkoxysilane relative to the total amount of the composition containing the silica precursor, the organic polymer, the organic solvent and the acid is subjected to hydrolysis and condensation reaction. It is determined as a ratio of the weight of the obtained siloxane.

Next, the organic polymer (B) in the present invention will be described. First, the organic polymer that can be used in the present invention is stable in the state of being dissolved in the coating composition of the present invention, does not precipitate even at low temperatures, and the coating film is porous by heating and baking as described below. In the case of converting into a silica thin film, it is preferable that the thermal decomposition temperature is low. Specifically, it is a linking group having at least three linking moieties capable of forming a carbon-oxygen bond, and at least 3 of the linking moieties. It is preferable to include a branched organic polymer (hereinafter, referred to as a branched block copolymer) in which one is bonded to an aliphatic ether block copolymer having two or more elements via a connecting portion.

It is preferable that the block portion constituting the branched block copolymer has a repeating unit of a linear or cyclic oxyalkylene group having 1 to 8 carbon atoms, and the block copolymer unit is based on the entire branched block copolymer. It is preferable to contain 60% by weight or more. Specific examples of the primary structure of the block copolymer portion include binary block copolymers such as polyethylene glycol polypropylene glycol, polyethylene glycol polybutylene glycol, polyethylene glycol polypropylene glycol polyethylene glycol, polypropylene glycol polyethylene glycol polypropylene glycol, polyethylene glycol polybutylene glycol. Mention may be made of polyhydric alcohols of aliphatic polyether block copolymers such as ternary block copolymers such as polyethylene glycol. Of these, linear ones are preferable.

Further, it is also possible to use a linear higher aliphatic / alkylene oxide block copolymer type polymer chain obtained by addition-polymerizing an alkylene oxide to an aliphatic higher alcohol. Specifically, polyoxyethylene lauryl ether, polyoxypropylene lauryl ether, polyoxyethylene oleyl ether, polyoxypropylene oleyl ether, polyoxyethylene cetyl ether, polyoxypropylene cetyl ether, polyoxyethylene stearyl ether, polyoxypropylene stearyl. Mention may also be made of polyhydric alcohols such as ethers.

The branched block copolymer of the present invention contains at least 3 parts of the polyhydric alcohol of the above block copolymer.
It has a structure linked with a linking group composed of an aliphatic alkyl group having a linking part capable of forming a carbon-oxygen bond, an alicyclic compound, an aromatic group, a sugar chain structure and the like. The carbon-oxygen bond forming part in the present invention includes, for example, a structure such as an ether bond, an ester bond, a carbonate bond, and a carbonyl carbon-oxygen bond such as a urethane bond by the connection. , A phenoxy group capable of forming an aromatic carbon-oxygen bond, and these bonds may be mixed in the same molecule.

For example, when the connecting portion is an ether bond, examples of the connecting group include compounds having a hydroxyl group such as glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, mannitol and xylitol to obtain a branched block copolymer. In addition, the branched block copolymer of the present invention in which propylene oxide is addition-polymerized to a plurality of hydroxyl groups contained in the linking group and then ethylene oxide is addition-polymerized to link the block copolymer to the linking group can be obtained.

Further, the hydroxyl terminal group of the aliphatic ether block copolymer is dehydrated with the hydroxyl group of the linking group, or the hydroxyl group of the polymer chain of the higher aliphatic / alkylene oxide block copolymer type and the hydroxyl group of the linking group are dehydrated. It can also be obtained by reacting. Specific examples of the branched block copolymer include glycerol polyethylene glycol polypropylene glycol, erythritol polyethylene glycol polypropylene glycol polyethylene glycol, sorbitol polyethylene glycol polypropylene glycol polyethylene glycol, glycerol polyethylene glycol stearic acid ester, and erythritol polyethylene glycol stearic acid ester.

Specific examples of polyhydric alcohols other than the above which function as a linking group include 1,2,4-benzenetriol, pyrogallol, threitol, maltitol, arabitol, lactitol, adonitol, cellobitor, glucose, fructose, Sucrose, lactose, mannose, galactose, erythrose,
Examples include xylulose, allulose, ribose, sorbose, xylose, arabinose, isomaltose, dextrose, glucoheptose, and the like.

Further, as the linking group which forms a carbon-oxygen bond at the linking part by forming an ester bond, citric acid, malic acid, tartaric acid, gluconic acid, glucuronic acid, glucoheptonic acid, glucooctanoic acid, threonic acid, saccharinic acid. , Galactonic acid, galactaric acid, galacturonic acid, glyceric acid, hydroxysuccinic acid, and aromatic compounds include 1,2,3-benzenetricarboxylic acid, 1,
2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid and the like can be mentioned. Further, a polymer having an OH group or a COOH group in the monomer unit and having a degree of polymerization of the monomer of 3 to 1000 units can also be used as the linking group, and specifically, polyvinyl alcohol, polyacrylic acid can be used. , Polymethacrylic acid, polyhydroxyethyl methacrylate, poly (p-hydroxymethyl) styrene, polyphenols and their copolymers.

When the content of the above branched block copolymer in the coating composition of the present invention is 10% by weight or more based on the total amount of the polymer including the organic polymer other than the branched block copolymer described below, the effect of the present invention is obtained. One of the effects is to reduce the viscosity of the porous silica thin film composition solution and to prevent freezing. When it is less than 10% by weight,
The effect of the present invention is not sufficiently expressed. A more preferable content is 11% by weight or more. More preferably, it is 15% by weight or more. In the present invention, the organic polymer may be only the branched block polymer.

Next, an organic polymer other than the above-mentioned branched block copolymer used in the present invention will be described. Specific examples of the main chain skeleton constituting the organic polymer, polyether, polyester, polycarbonate, polyanhydride, polyamide, polyurethane, polyurea, polyacrylic acid, polyacrylic acid ester, polymethacrylic acid, polymethacrylic acid ester, polyacrylamide, poly Methacrylamide, polyacrylonitrile, polymethacrylonitrile, polyolefin, polydiene,
Polyvinyl ether, polyvinyl ketone, polyvinyl amide, polyvinyl amine, polyvinyl ester, polyvinyl alcohol, polyvinyl halide, polyvinylidene halide, polystyrene, polysiloxane, polysulfide, polysulfone, polyimine, polyimide, cellulose, and their derivatives A polymer as a constituent component may be used.

Among the above-mentioned polymers, those preferably used are mainly aliphatic polyethers, aliphatic polyesters, aliphatic polycarbonates and aliphatic polyanhydrides which disappear by heating and calcination and are easily converted into porous silicon oxides. Is a constituent component. Further, in the present invention, the effect is obtained even if at least one of the polymer end groups of the organic polymer other than the above-mentioned branched block copolymer has a group which is chemically inactive to the silica precursor.

That is, the organic polymer is more easily removed from the silica / organic polymer composite thin film by using the inert end group together. Examples of the terminal group which is chemically inactive to the silica precursor include terminal groups such as alkyl ether, alkyl ester, alkyl amide, alkyl carbonate, urethane and trialkylsilyl. The polymer in which at least one end group of the organic polymer end groups other than the branched block copolymer of the present invention is a group which is chemically inert to the silica precursor will be described in more detail below.

As a specific example of the case where an aliphatic polyether is used as a main chain skeleton as an organic polymer other than the branched block copolymer of the present invention, the main chain is not bonded to the same carbon atom of an alkane having 2 or more carbon atoms. Two hydrogen atoms,
Examples thereof include alkylene glycols, which are dihydric alcohols obtained by substituting hydroxyl groups, and specifically, polyethylene glycol, polypropylene glycol, polyisobutylene glycol, polytrimethylene glycol, polytetramethylene glycol, polypentamethylene glycol, poly Hexamethylene glycol, polydioxolane, polydioxepane and the like can be used as the alkylene glycol of the present invention. Further, as the inert group, at least one terminal of the above alkylene glycols may be an alkyl ether, an alkyl ester, an alkyl amide, or an alkyl carbonate.

In the present invention, alkyl means a C1 to C8 alkyl group and an aryl group such as phenyl group, tolyl group and anisyl group. The inactive group at the terminal of the organic polymer of the present invention may be directly chemically bonded to the terminal of the organic polymer, or may be bonded via the organic group. Further, the alkylene may be alkylene glycols other than the above, such as methylene, hexamethylene, isopropylidene, 1,2-dimethylethylene, and 2,2-dimethyltrimethylene.

The case where an aliphatic polyether is used for the main chain skeleton as an organic polymer other than the branched block copolymer of the present invention and the terminal group thereof is etherified, esterified, amidated or carbonated will be individually described.
First, examples of etherification include those in which at least one terminal of the above alkylene glycols is etherified with, for example, methyl ether, ethyl ether, propyl ether, glycidyl ether, and the like. Specifically, for example, polyethylene glycol monomethyl Ether, polyethylene glycol dimethyl ether, polypropylene glycol dimethyl ether, polyisobutylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol dibutyl ether, polyethylene glycol monobutyl ether, polyethylene glycol diglycidyl ether, polyethylene polypropylene glycol dimethyl ether, glycerin polyethylene glycol Lumpur trimethyl ether, pentaerythritol polyethylene grayed reel tetramethyl ether, pentitol polyethylene glycol pentamethyl ether, sorbitol polyethylene glycol hexamethyl ether is particularly preferably used.

Further, as an example in which an aliphatic polyether is used in the main chain skeleton as an organic polymer other than the branched block copolymer of the present invention and the terminal is esterified, at least one terminal of the above alkylene glycol is, for example, Examples include acetic acid ester, propionic acid ester, acrylic acid ester, methacrylic acid ester, and benzoic acid ester. Further, those in which the end of alkylene glycol is converted to carboxymethyl ether and the carboxyl group at this end is converted to alkyl ester are also preferably used. Specifically, for example, polyethylene glycol monoacetate, polyethylene glycol diacetate, polypropylene glycol monoacetate, polypropylene glycol diacetate, polyethylene glycol dibenzoate, polyethylene glycol diacrylate, polyethylene glycol monomethacrylate , Polyethylene glycol dimethacrylic acid ester, polyethylene glycol biscarboxymethyl ether dimethyl ester, polypropylene glycol biscarboxymethyl ether dimethyl ester, glycerin polyethylene glycol triacetate ester, pentaerythritol polyethylene glycol tetraacetate ester, pentitol polyethylene glycol pentaacetate ester, sol And tall polyethylene glycol hexa acetate are preferred examples.

Further, as an example in which an aliphatic polyether is used for the main chain skeleton as an organic polymer other than the branched block copolymer of the present invention, an end is amidated, at least one end of the above alkylene glycols is carboxymethyl. Etherification followed by amidation,
Examples include a method in which the hydroxy terminal is modified with an amino group and then amidated. Specifically, polyethylene glycol bis (carboxymethyl ether dimethylamide), polypropylene glycol bis (carboxymethyl ether dimethylamide), polyethylene glycol bis ( (Carboxymethyl ether diethyl amide), glycerin polyethylene glycol tricarboxymethyl ether dimethylamide, pentaerythritol polyethylene glycol tetracarboxymethyl ether dimethylamide, pentitol polyethylene glycol pentacarboxymethyl ether dimethylamide, sorbitol polyethylene glycol hexacarboxymethyl ether dimethylamide, etc. Used for.

Examples of organic carbonates other than the branched block copolymer of the present invention in which the main chain skeleton uses aliphatic polyethers to form alkyl carbonates at the ends include, for example, at least one end of the above alkylene glycols, Examples thereof include a method of attaching a formyl ester group, and specific examples thereof include bismethoxycarbonyloxy polyethylene glycol, bisethoxycarbonyloxy polyethylene glycol, bisethoxycarbonyloxy polypropylene glycol, and bis-tert-butoxycarbonyloxy polyethylene glycol.

Further, as an organic polymer other than the branched block copolymer of the present invention, an aliphatic polyether may be used for the main chain skeleton to urethanize or trialkylsilylate the terminal. Is particularly preferable, and this can be performed using trimethylchlorosilane, trimethylchlorosilylacetamide, hexamethyldisilazane, or the like.

On the other hand, examples of using an aliphatic polyester in the main chain skeleton as an organic polymer other than the branched block copolymer of the present invention include polycondensates of hydroxycarboxylic acids such as polyglycolide, polycaprolactone and polypivalolactone, and Ring-opening polymer of lactone, polycondensate of dicarboxylic acid such as polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene sebacate, polypropylene adipate, polyoxydiethylene adipate and alkylene glycol, and epoxide and acid anhydride A ring-opening copolymer of
As the inactive group, at least one terminal of these polymers may be alkyl etherified, alkyl esterified, alkyl amidated, alkyl carbonated, urethanized or trialkylsilylated. The above-mentioned dicarboxylic acid refers to an organic acid having two carboxyl groups such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid.

Examples of using an aliphatic polycarbonate in the main chain skeleton as the organic polymer other than the branched block copolymer of the present invention include polyethylene carbonate,
Polycarbonate such as polypropylene carbonate, polypentamethylene carbonate, polyhexamethylene carbonate and the like can be mentioned, and at least one terminal of these polymers is alkyl etherified, alkyl esterified, alkyl amidated, alkyl carbonated, urethanized and further. The thing which trialkylsilylated can be mentioned.

As an example of using an aliphatic polyanhydride in the main chain skeleton as an organic polymer other than the branched block copolymer of the present invention, polymalonyl oxide,
Examples thereof include polycondensates of dicarboxylic acids such as polyadipoyl oxide, polypimeloyl oxide, polysuberoyl oxide, polyazela oil oxide, and polysebacyl oxide, and at least one terminal of these polymers is alkyl. Examples thereof include those modified with an ether group, an alkyl ester group, an alkyl amide group, an alkyl carbonate group, a urethane group, and a trialkylsilyl group. A polymerizable functional group can also be used as the terminal group of the present invention which is chemically inactive to the silica precursor. The use of such a group improves the strength of the porous thin film, although the reason is not clear.

Functional groups which are used in organic polymers other than the branched block copolymer of the present invention and which are chemically inactive with respect to the silica precursor and which can be polymerized are vinyl group, vinylidene group, vinylene group, glycidyl group and allyl group. , Acrylate group, methacrylate group, acrylamide group, methacrylamide group, carboxyl group, hydroxyl group, isocyanate group, amino group, imino group, halogen group and the like. These functional groups may be directly bonded to the polymer chain or may be bonded via a spacer such as an alkylene group or an ether group. The same polymer molecule may have one type of functional group or two or more types of functional groups. Among the functional groups listed above, a vinyl group, a vinylidene group, a vinylene group, a glycidyl group, an allyl group, an acrylate group, a methacrylate group, an acrylamide group, and a methacrylamide group are preferably used.

The organic polymer other than the branched block copolymer of the present invention containing a functional group capable of polymerizing as an inactive group will be more specifically shown below. (A) polyalkylene glycol (meth) acrylate, polyalkylene glycol di (meth) acrylate, polyalkylene glycol alkyl ether (meth) acrylate, polyalkylene glycol vinyl ether, polyalkylene glycol divinyl ether,
Polyalkylene glycol alkyl ether vinyl ether, polyalkylene glycol glycidyl ether,
Aliphatic polyethers having a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group and a glycidyl group at the terminal, represented by polyalkylene glycol diglycidyl ether and polyalkylene glycol alkyl ether glycidyl ether. (The above (meth) acrylate notation indicates both acrylate and methacrylate.)

(B) Polycaprolactone (meth) acrylate, polycaprolactone vinyl ether, polycaprolactone glycidyl ether, polycaprolactone vinyl ester, polycaprolactone glycidyl ester, polycaprolactone vinyl ester (meth) acrylate, polycaprolactone glycidyl ester (meth) acrylate, Polycaprolactone vinyl ester vinyl ether, polycaprolactone glycidyl ester vinyl ether, polycaprolactone vinyl ester glycidyl ether, polycaprolactone glycidyl ester glycidyl ether, etc., acrylate group, methacrylate group at one end or both ends,
Polycaprolactone having a polymerizable functional group such as a vinyl group or a glycidyl group.

(C) Polycaprolactone triol (meth) acrylate, di (meth) acrylate, tri (meth) acrylate, vinyl ether, divinyl ether, trivinyl ether, glycidyl ether, diglycidyl ether, triglycidyl ether. (D) An aliphatic polyester which is a polymer of dicarboxylic acid and alkylene glycol and has a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group or a glycidyl group at one or both ends.

(E) An aliphatic polyalkylene carbonate having a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group or a glycidyl group at one or both ends. (F) An aliphatic polyanhydride which is a polymer of dicarboxylic acid anhydride and has a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group, a glycidyl group at the terminal.

(G) Polyglycidyl (meth) acrylate, polyallyl (meth) acrylate, polyvinyl (meth) acrylate, etc., having a vinyl group, a glycidyl group in the side chain,
Polyacrylic acid esters and polymethacrylic acid esters having functional groups such as allyl groups. (H) Polyvinyl cinnamate, polyvinyl azidobenzal, epoxy resin and the like. Although the organic polymers other than the branched block copolymer that can be used in the present invention have been described above, the molecular weight of the organic polymer other than the branched block polymer is 1 in number average.
It is 100 to 100,000, preferably 100 to 300,000, and more preferably 200 to 50,000.

When the molecular weight is 100 or less, the organic polymer is removed from the silica / organic polymer composite too quickly to obtain a porous silica thin film having a desired porosity, and the polymer is removed. If the molecular weight exceeds 1,000,000, then the removal rate of the polymer is too slow and the polymer remains, which is not preferable. In particular, a more preferable polymer has a molecular weight of 200 to 50,000, and in this case, a porous silica thin film having a desired high porosity can be obtained very easily at low temperature in a short time. It should be noted here that the pore size of porous silica is
It is extremely small and uniform, with little dependence on the molecular weight of the polymer.

In the present invention, also in the above-mentioned branched block copolymer, at least one of the terminal groups may be a chemically inactive group. Preferred terminal groups include the linear and cyclic alkyl ether groups, alkyl ester groups, alkylamide groups, alkyl carbonate groups, urethane groups and trialkylsilyl group-modified groups described above. The molecular weight of each block of the block copolymer is 100 to 100,000, preferably 100.
˜50,000, more preferably 200 to 20,000. When the molecular weight is 100 or less or 100,000 or more, an appropriate compatibility is not obtained between the silica precursor and the polymer, so that the mechanical strength of the porous silica thin film is not expressed.

The amount of the organic polymer added in the present invention is
Siloxane 1 obtained by assuming that the total amount of the starting material alkoxysilane charged has undergone hydrolysis and condensation reactions
0.01 to 10 parts by weight, preferably 0.0
It is 5 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. If the addition amount of the organic polymer is less than 0.01 part by weight, a porous body cannot be obtained, and even if it is more than 10 parts by weight, porous silica having sufficient mechanical strength cannot be obtained, resulting in poor practicability. The siloxane obtained assuming that the total amount of alkoxysilane charged has undergone hydrolysis and condensation reactions means SiOR ² groups and SiOR ⁴ groups S in the general formulas (1) and (2).
The iOR ⁵ group is 100% hydrolyzed to SiOH,
Furthermore, it means that the siloxane structure is obtained by 100% condensation.

Next, the solvent (C) that can be used in the present invention will be described. The solvent (C) that can be used in the present invention is dissolved or dispersed in at least one solvent selected from the group consisting of alcohol solvents, ketone solvents, amide solvents and ester solvents. Here, as the alcohol solvent, methanol, ethanol, n
-Propanol, i-propanol, n-butanol,
i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-
Methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, heptanol-
3, n-octanol, 2-ethylhexanol, se
c-octanol, n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, s
ec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol and other monoalcoholic solvents, and ethylene glycol, 1, 2-propylene glycol, 1,3-butylene glycol, pentanediol-2,4, 2-methylpentanediol-2,4, hexanediol-2,
5, polyhydric alcohol solvents such as heptanediol-2,4,2-ethylhexanediol-1,3, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, and ethylene glycol monomethyl ether, ethylene glycol monoethyl Ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether,
Diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether Examples thereof include polyhydric alcohol partial ether solvents. These alcohol solvents may be used either individually or in combination of two or more.

Of these alcohols, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, s
ec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether. , Propylene glycol monobutyl ether and the like are preferable.

As the ketone solvent, acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-
n-butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-
Butyl ketone, methyl-n-hexyl ketone, di-i-
Butyl ketone, trimethylnonanone, cyclohexanone, 2-hexanone, methylcyclohexanone, 2,4
-Pentanedione, acetonylacetone, acetophenone, fenchon, etc., acetylacetone, 2,
4-hexanedione, 2,4-heptanedione, 3,5
-Heptanedione, 2,4-octanedione, 3,5-
Octanedione, 2,4-nonanedione, 3,5-nonanedione, 5-methyl-2,4-hexanedione, 2,
2,6,6-tetramethyl-3,5-heptanedione,
Examples include β-diketones such as 1,1,1,5,5,5-hexafluoro-2,4-heptanedione.
These ketone solvents may be used either individually or in combination of two or more.

As the amide solvent, formamide, N
-Methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N,
N-dimethylacetamide, N-ethylacetamide,
Examples include N, N-diethylacetamide, N-methylpropionamide, N-methylpyrrolidone, N-formylmorpholine, N-formylpiperidine, N-formylpyrrolidine, N-acetylmorpholine, N-acetylpiperidine, N-acetylpyrrolidine and the like. To be These amide solvents may be used either individually or in combination of two or more.

Ester solvents include diethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ.
-Valerolactone, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, acetic acid 2-ethylbutyl, 2-ethylhexyl acetate, benzyl acetate,
Cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monoacetate
n-Butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, acetic acid Methoxytriglycol, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, malonic acid Examples thereof include diethyl, dimethyl phthalate, and diethyl phthalate. These ester solvents are 1
One kind or two or more kinds may be used at the same time. In addition, it is preferable to use an alcohol solvent and / or an ester solvent as the solvent (C), because a composition having good coatability and excellent storage stability can be obtained.

The coating composition of the present invention comprises the above solvent (C).
However, the silica precursor (A) is hydrolyzed and / or
Alternatively, at the time of condensation, the same solvent can be additionally added. In the present invention, it is possible to add an acid for the purpose of controlling the hydrolysis and / or condensation rate of the silica precursor (A). Specific examples of the acid that can be used in the present invention include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, tripolyphosphoric acid, phosphinic acid, and phosphonic acid. As the organic acid, for example, acetic acid,
Propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oxalic acid, maleic acid, methylmalonic acid, adipic acid, sebacic acid, gallic acid, butyric acid, meritic acid, arachidonic acid , Shikimic acid, 2-ethylhexanoic acid, oleic acid, stearic acid, linoleic acid, linoleic acid, salicylic acid, benzoic acid, p-aminobenzoic acid, p-toluenesulfonic acid, benzenesulfonic acid, monochloroacetic acid, dichloroacetic acid, trichloro Examples thereof include acetic acid, trifluoroacetic acid, formic acid, malonic acid, sulfonic acid, phthalic acid, fumaric acid, citric acid, tartaric acid, succinic acid and isonicotinic acid.

Further, a compound which functions as an acid after the coating solution of the present invention is coated on a substrate is also included. Specific examples thereof include compounds such as aromatic sulfonic acid esters and carboxylic acid esters that decompose by heating or light to generate an acid. The acid may be used alone or in combination of two or more kinds. The amount of these acid components added is 1 mol% or less, preferably 0.5 mol, based on the total number of moles of alkoxysilane groups of the alkoxysilanes of the general formulas (1) and / or (2) charged as starting materials. % Or less, more preferably 0.2 mol% or less is suitable. If it is more than 1 mol%, a precipitate may be formed, and it may be difficult to obtain a coating film made of a homogeneous porous silicon oxide, or a coating film having a low relative dielectric constant may not be obtained.

As described above, by combining the above-mentioned specific ratio of the alkoxysilane and the organic polymer containing the branched polyether block copolymer and the organic solvent, the relative dielectric constant of the porous silica thin film produced therefrom is remarkably increased. Can be lowered. The reason for this is not clear, but silanol groups, which are silica end groups present in the composite or porous body (silanol groups are water-absorbing and cause a significant increase in the dielectric constant of a thin film) and the 1,2 It is presumed that the silanol group is deactivated by promoting the reaction with the functional alkoxysilane and the like by the action of the polyether block copolymer and the acid.

If desired, other components such as colloidal silica and a surfactant may be added to the coating composition of the present invention, and a photocatalyst generating agent for imparting photosensitivity and a substrate may be added. It is also possible to add optional additives such as an adhesion improver for improving the adhesion of the above and a stabilizer for long-term storage to the coating composition of the present invention within a range not impairing the gist of the present invention.

Next, the method for producing the coating composition of the present invention will be described. As the method for producing the coating composition of the present invention,
After the alkoxysilane is charged as a starting material, water may be added to carry out hydrolysis and condensation reaction, and then an organic polymer or solvent may be added. Alternatively, the organic polymer or solvent may be added to the alkoxysilane in advance. After that, hydrolysis and polycondensation reaction may be performed. In the present invention, water (D) is required for hydrolysis of the alkoxysilane. Water is generally added to the alkoxysilane as a liquid or as an alcohol or an aqueous solution, but it may be added in the form of steam. If water is added rapidly, hydrolysis and condensation may occur too quickly depending on the type of alkoxysilane to cause precipitation.Therefore, it may take sufficient time to add water, or a solvent such as alcohol to homogenize it. The method of coexisting with, the method of adding at low temperature, etc. are used alone or in combination.

The added water (D) is once consumed for the hydrolysis of the alkoxysilane, but is purified as a by-product during the subsequent condensation reaction, so that it is not used in the coating composition of the present invention. Appropriate amount is present with the solvent. The amount of water contained in the coating composition is 10 based on the total weight of the coating composition.
Wt% to 70 wt%, preferably 20 wt% to 60
% By weight. If it is less than 10% by weight, the mechanical strength is not expressed, and if it is more than 70% by weight, the silica precursor is likely to precipitate.

Water may be added in the whole amount or intermittently during the hydrolysis and polycondensation reaction. Further, after the completion of the polycondensation reaction, it may be added additionally so as to have the above content. The alkoxysilane hydrolyzes to silanol in the presence of water, and then grows into an oligomeric silica precursor having a siloxane bond by a condensation reaction between silanol groups. In the coating composition of the present invention, it is better to make the alkoxysilane oligomeric in advance (l) since the viscosity of the coating solution is appropriately increased, so that the shape retention of the coating film can be secured and the film thickness can be made uniform. When the silica precursor gels,
Since the formation of the silica skeleton occurs mildly, film shrinkage is less likely to occur, which is more preferable.

In the present invention, the temperature at which the alkoxysilane is hydrolyzed is usually 0 to 150 ° C., preferably 0.
To 100 ° C, more preferably 0 ° C to 50 ° C. 0 ° C
If it is lower than this, the progress of hydrolysis is not sufficient, and conversely 15
If the temperature exceeds 0 ° C., the reaction may proceed too rapidly and gelation of the solution may occur, which is not preferable. The condensation rate of the silica precursor contained in the coating composition of the present invention is 10 to 90%,
Preferably 20-85%, more preferably 30-85%
Is. If the condensation rate is lower than 10%, the above (1) and (2) cannot be achieved, which is not preferable. If the condensation rate exceeds 90%, the entire coating composition will gel.

The condensation rate of the silica precursor is calculated by the same measuring method as in the case of obtaining the silica composition ratio described later. The acid in the present invention may be added in the total amount during the hydrolysis and condensation reaction of the alkoxysilane, or may be added stepwise. Further, it may be added just before coating the coating composition. In addition, the content of alkali metals such as sodium and potassium and iron in the coating composition is preferably 15 ppb or less, particularly 10 ppb or less from the viewpoint of low leak current of the coating film. The alkali metal and iron may be mixed from the raw materials used, and it is preferable to purify the silica precursor (A), the organic polymer (B), the solvent (C) and the like by distillation or the like.

In the present invention, a silica / organic polymer composite thin film can be obtained by using the coating composition obtained as described above as a coating liquid and gelating the silica precursor in the obtained coating film. it can. Hereinafter, a method for coating the coating composition of the present invention to obtain a thin film, a method for gelating the thin film to form a composite thin film, and a method for removing an organic polymer from the composite thin film will be described in detail.

The total solid content concentration of the coating composition in the present invention is preferably 2 to 30% by weight as described above, but it is appropriately adjusted according to the purpose of use. When the total solid content concentration of the coating composition is 2 to 30% by weight, the film thickness of the coating film is in an appropriate range and the storage stability is further excellent. The total solid content concentration is adjusted, if necessary, by concentration or dilution with the solvent (C). In the present invention, the thin film is formed by applying the coating composition of the present invention onto a substrate. As a coating method, known methods such as casting, dipping, and spin coating can be used, but spin coating is suitable for use in manufacturing an insulating layer for a multilayer wiring structure of a semiconductor element. The thickness of the thin film is 0.1 μm to 1 depending on the viscosity of the coating composition and the rotation speed.
It can be controlled in the range of 00 μm. If it is thicker than 100 μm, cracks may occur. The insulating layer for a multilayer wiring structure of a semiconductor device is usually used in the range of 0.1 μm to 5 μm.

As the substrate, a semiconductor substrate of silicon, germanium or the like, a compound semiconductor substrate of gallium-arsenic, indium-antimony or the like can be used, and a thin film of another substance is formed on the surface thereof before use. Is also possible. In this case, as the thin film, in addition to metals such as aluminum, titanium, chromium, nickel, copper, silver, tantalum, tungsten, osmium, platinum and gold, silicon dioxide, fluorinated glass, phosphorus glass, boron-phosphorus glass, borosilicate. Acid glass, polycrystalline silicon, alumina,
Inorganic compounds such as titania, zirconia, silicon nitride, titanium nitride, tantalum nitride, boron nitride, hydrogenated silsesquioxane, methyl silsesquioxane, amorphous carbon, fluorinated amorphous carbon, polyimide, and any other block copolymer Thin films can be used.

Prior to the formation of the thin film, the surface of the substrate is
It may be previously treated with an adhesion improver. As the adhesion improver in this case, those used as so-called silane coupling agents, aluminum chelate compounds and the like can be used. Particularly preferably used are 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N-
(2-Aminoethyl) -3-aminopropylmethyldimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldichlorosilane, 3-chloropropylmethyldimethoxysilane, 3- Chloropropylmethyldiethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyl Dimethoxysilane, hexamethyldisilazane, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), aluminum bis (ethyl acetoacetate) G) monoacetylacetonate, and the like of aluminum tris (acetylacetonate). When applying these adhesion improvers, other additives may be added, if necessary, or diluted with a solvent. The treatment with the adhesion improver is performed by a known method.

The gelling temperature to be subsequently applied after forming the coating composition into a coating film is not particularly limited, but is usually 100 to 30.
0 ° C., preferably 150 to 300 ° C. The time required for the gelation reaction varies depending on the heat treatment temperature, the amount of catalyst added and the solvent species and amount, but is usually in the range of several seconds to 10 hours. Preferably 30 seconds to 5 hours, more preferably 1
Minutes to 2 hours. By this operation, the gelation reaction of the silica precursor in the coating composition sufficiently progresses to form silica.
The condensation rate of silica may reach nearly 100%. Usually, it exceeds 90%. The condensation rate in this case can be determined by solid-state NMR. Temperature is 100
If the temperature is lower than 0 ° C., the polymer starts to be removed before the gelation sufficiently progresses in the subsequent polymer removal step, resulting in the densification of the coating film. On the other hand, if the temperature is higher than 300 ° C., huge voids are apt to be generated, and the homogeneity of the silica / organic polymer composite thin film described later is deteriorated.

Since the silica / organic polymer composite thin film thus obtained has a low dielectric constant and is capable of forming a thick film, it can be used as it is as an insulating portion of wiring, For example optical films and structural materials,
It can also be used as a film or coating material. However, it is preferable to convert it into a porous silica thin film for the purpose of obtaining a material having a lower dielectric constant as an insulator of the LSI multilayer wiring.

From the silica / organic polymer composite thin film to the insulating porous silica thin film, the polymer is removed from the silica / organic polymer composite thin film. At this time, if the gelation reaction of the silica precursor has proceeded sufficiently, the region occupied by the organic polymer in the silica / organic polymer composite thin film does not collapse as voids in the porous silica thin film. Remain. As a result, a porous silica thin film having a high porosity and a low dielectric constant can be obtained.

As a method for removing the organic polymer, heating, plasma treatment, solvent extraction and the like can be mentioned, but heating is the most preferable from the viewpoint that it can be easily carried out in the current semiconductor element manufacturing process. In this case, the heating temperature depends on the type of the organic polymer used, and may be simply evaporated and removed in a thin film state, may be removed by firing with decomposition of the organic polymer, and may be a mixture thereof. The heating temperature is 300 to less than 450 ° C,
It is preferably in the range of 350 to 400 ° C. If the temperature is lower than 300 ° C., the removal of the organic polymer is insufficient and impurities of the organic matter remain, so that there is a risk that a porous silica thin film having a low dielectric constant cannot be obtained. Also, the amount of pollutant gas generated is large. Conversely 4
Treatment at a temperature higher than 50 ° C. is preferable from the viewpoint of removing the organic polymer, but it is extremely difficult to use in the semiconductor manufacturing process.

The heating time is preferably in the range of 10 seconds to 24 hours. It is preferably 10 seconds to 5 hours, and particularly preferably 1 minute to 2 hours. If it is shorter than 10 seconds, the evaporation and decomposition of the organic polymer will not proceed sufficiently, so that organic substances remain as impurities in the resulting porous silica thin film, and the dielectric constant does not decrease. Moreover, since the thermal decomposition and the evaporation are usually completed within 24 hours, heating for a longer time does not make much sense. The heating is preferably performed under an inert atmosphere such as nitrogen, argon or helium. It is also possible to carry out in an oxidizing atmosphere such as mixing air or oxygen gas, but in this case, the concentration of the oxidizing gas is set so that the organic polymer is substantially decomposed before the silica precursor is gelated. It is preferable to control the concentration so that it does not occur. Further, by allowing ammonia, hydrogen, etc. to exist in the atmosphere to deactivate the silanol groups remaining in the silica, it is possible to reduce the hygroscopicity of the porous silica thin film and suppress an increase in the dielectric constant.

Since the amount of residual polymer in the porous silica thin film after removing the organic polymer of the present invention under the above heating conditions is remarkably reduced, the adhesive force of the upper layer film due to the decomposition gas of the organic polymer as described above. Phenomenon such as deterioration of the surface and peeling does not occur. The effect becomes more remarkable when the organic polymer in the coating composition of the present invention includes the polyether block copolymer and the polymer having a terminal group that is chemically inactive to the silica precursor.

In the present invention, if the step of forming the silica / organic polymer composite thin film and then the step of removing the polymer are performed under the above-mentioned conditions, before and after the step, a step at an arbitrary temperature and atmosphere is performed. There is no problem. For heating in the present invention, a single wafer type vertical furnace or a hot plate type firing system which is usually used in the semiconductor element manufacturing process can be used. Of course, it is not limited to these as long as the manufacturing process of the present invention is satisfied.

As described above, by using the porous silica thin film of the present invention, it is possible to form an insulating film for a multi-layer wiring for LSI, which has a high mechanical strength and a sufficiently low dielectric constant. The relative permittivity of the porous silica thin film of the present invention is usually 2.8 to 1.2, preferably 2.3 to 1.2, more preferably 2.3 to 1.2.
It is 1.6. This relative dielectric constant can be adjusted by the content of the component (B) in the coating composition of the present invention. Further, in the porous thin film of the present invention, pores of 20 nm or more are not substantially observed in the pore distribution measurement by the BJH method, and it is suitable as an interlayer insulating film. Usually, there are no pores of 10 nm or more.

The porous silica thin film obtained by the present invention is a bulk porous silica body other than the thin film, for example, an optical film such as an antireflection film or an optical waveguide, a catalyst carrier, a heat insulating material, an absorbent, a column packing. It can also be used as a material, an anti-caking agent, a thickener, a pigment, an opacifying agent, a ceramic, a smoke suppressant, an abrasive, a dentifrice, and the like.

[0089]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to these Examples. The relative dielectric constant of the porous silica thin film was measured by the following method. It measured using the SSM495 type | mold automatic mercury CV measuring device by a solid state measurement company.

[0090]

[Reference Example 1] In an autoclave, glycerin was added under dry nitrogen, and 15 mol equivalent of propylene oxide was added to glycerin in the presence of potassium ion to perform ring-opening polymerization. After the polymerization reaction of propylene oxide was completed, 48 equivalents of ethylene oxide was introduced to glycerin while keeping the system under nitrogen. Subsequently, ethylene oxide ring-opening polymerization was performed to obtain a tri-branched polypropylene oxide-polyethylene oxide block copolymer having a glycerin residue as a branch center. The number average molecular weight of this polymer by GPC was about 3000, and the polyethylene oxide portion obtained from NMR and the like corresponded to 70% by weight of the whole. This is Polymer 1.

[0091]

[Reference Example 2] Pentaerythritol was used instead of glycerin in Reference Example 1, and 33 times equivalent amount of propylene oxide and then 102 times equivalent amount of ethylene oxide were continuously reacted with pentaerythritol to continuously react with pentaerythritol residue. A 4-branched polypropylene oxide-polyethylene oxide block copolymer having a group as the center of branching was obtained. The number average molecular weight of this polymer was about 6400, and the polyethylene oxide portion was 70% by weight based on the whole. This is Polymer 2.

[0092]

Example 1 Tetraethoxysilane 9.72 g, methyltriethoxysilane 14.88 g, bistriethoxysilylethane 14.89 g, polymer 1 9.8 g, water 4
7.6 g, ethanol 66.6 g and oxalic acid 0.1
After mixing with 1.65 g of N nitric acid and reacting at 50 ° C. for 6 hours, the solution was concentrated under reduced pressure to 25% by weight, a predetermined amount of propylene glycol methyl ether and water were added, and the whole water was added. Content is 50%, silica solid content is 1
Adjusted to 2%. 3 ml of the obtained coating solution was dropped on a 6-inch silicon wafer and spin-coated at 1400 rpm for 60 seconds. Then, in air at 120 ° C for 1 minute, under nitrogen atmosphere at 200 ° C for 1 hour, and then under nitrogen atmosphere 4
The porous silica thin film having a thickness of 0.95 μm was obtained by firing at 00 ° C. for 1 hour. The dielectric constant of the film was 2.23.
The resulting solution was stored frozen in a -20 ° C freezer overnight.
The solution was homogeneous.

[0093]

Example 2 A composition solution was obtained in the same manner as in Example 1 except that the polymer 2 was used instead of the polymer 1.
Example 1 after spin-coating this solution at 1800 rpm
The porous silica thin film having a film thickness of 0.92 μm was obtained by firing under the same conditions as described above. The dielectric constant of the film was 2.24. The obtained solution was frozen and stored in a -20 ° C freezer overnight, but the solution was uniform.

[0094]

Comparative Example 1 The same operation as in Example 1 was repeated except that the number average molecular weight was 6
A composition solution was obtained by the same operation except that 400 polyethylene glycol polypropylene glycol polyethylene glycol block copolymer (70% by weight of polyethylene oxide portion) was used. 200 this solution
After spin coating at 0 rpm, baking was performed under the same conditions as in Example 1 to obtain a porous silica thin film having a thickness of 1.05 μm. The dielectric constant of the film was 2.22. From the relationship between the rotation speed and the film thickness, it is clear that the viscosity of the solution of Comparative Example 1 is high in Comparative Example 1 even though the polymer having the same molecular weight as in Example 2 was used. This was also apparent when the solutions of Examples 1 and 2 and the solution of Comparative Example 1 were shaken by hand and the speed at which bubbles disappeared was visually compared. When the obtained solution was stored in a -20 ° C freezer overnight, a slight increase in scattered light presumed to be derived from freezing / aggregation of the polymer was visually observed.

[0095]

The silica composition according to the present invention has a relatively low viscosity and is hard to freeze so that a solution having excellent handling property is provided. The porous silica thin film obtained from the silica composition has a sufficiently low relative dielectric constant and is stable. It is most suitable for use as a substrate for LSI multilayer wiring and as an insulating film for semiconductor elements.

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 201/00 C09D 201/00 H01L 21/316 H01L 21/316 G F term (reference) 4G072 AA25 BB09 BB15 EE06 EE07 GG01 GG02 GG03 HH30 JJ47 LL11 LL15 MM01 PP05 RR12 UU01 4J038 DL021 DL031 DL161 NA21 PB09 5F058 AA10 AC03 AF04 AG01 AH02 BA20 BC02 BC20 BF46 BH01 BJ02

Claims (6)

[Claims] 1. (A) At least one selected from the group consisting of 1 to 6-functional alkoxysilane represented by the following general formula (1) and / or general formula (2) and its hydrolyzate and polycondensate. And a silica precursor containing a compound of R ¹ _n (Si) (OR ² ) _4-n (1) (In the formula, R ¹ and R ² may be the same or different and each is hydrogen or monovalent. represents an organic group, n is an integer of _{^{0~3) R 3 m (R 4}} O) 3-m Si- (R 7) p -Si (OR 5) 3-q R 6 q (2) (R ³ , R ⁴ , R ⁵ and R ^{6, which} may be the same or different, each represents hydrogen, a monovalent organic group, and m and q
May be the same or different and represent a number from 0 to 2,
R ⁷ represents a group represented by an oxygen atom — or (CH ₂ ) _r —, r represents 1 to 6, and p represents 0 or 1. (B) A branched organic polymer which is a linking group having at least three linking moieties capable of forming a carbon-oxygen bond, and at least three of the linking moieties are bound to a binary or more block copolymer. An organic polymer contained in an amount of 10% by weight or more based on the total weight, and a coating composition for producing an insulating thin film. 2. The coating composition for producing an insulating thin film according to claim 1, further comprising at least one organic solvent selected from the group consisting of (C) an alcohol-based solvent, a ketone-based solvent, an amide-based solvent and an ester-based solvent. The coating composition for producing an insulating thin film according to claim 1, comprising: 3. The coating composition according to claim 1, wherein at least one of the terminal groups of the organic polymer is a group which is chemically inert to the silica precursor. 4. An organic polymer is removed from a silica / organic polymer composite thin film obtained by gelling a silica precursor after applying a coating composition according to any one of claims 1 to 3 on a substrate. Porous silica thin film. 5. A wiring structure using the thin film according to claim 4 as an insulator. 6. A semiconductor device including the wiring structure according to claim 5.